[Feature] Interactive Search for all chats in the app

[byebb]

Feature description

I like to automatically find certain chats based on the content by searching only using keywords instead of having the need to browser through the full list of chats, which can become quite long..

Motivation

Imprived UI Experience

Alternatives

Downloading all chats in a single zip file as mutliple markdown files.

Additional context

I imagine placing the search right above the first chat in the top left corner of the window.

[byebb]

Connected to #645.

[rablinz]

I would also really like to see a search feature